The role of computed tomography in the diagnosis of acute appendicitis

BACKGROUND: Routine contrast-enhanced computed tomography (CECT) has been described as an accurate diagnostic imaging modality in patients with acute appendicitis. However, most patients with acute appendicitis can be diagnosed by clinical findings and physical exam alone. The role of CECT in patients suspected of having appendicitis but with equivocal clinical exams remains ill defined. METHODS: One hundred and seven consecutive patients who were thought to have appendicitis but with equivocal clinical findings and/or physical exams were imaged by CECT over a 12-month period. Oral and intravenous contrast-enhanced, spiral abdominal and pelvic images were obtained using 7-mm cuts. CECT images were interpreted by a board-certified radiologist. Main outcome measures included CECT sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in the diagnosis of acute appendicitis, comparing CECT with ultrasound, and determining the impact of CECT on the clinical management of this patient population. RESULTS: A group of 107 patients consisting of 44 males (41%) and 63 females (59%) with a median age of 33 years (range 13 to 89 years) were imaged with CECT to evaluate suspected appendicitis. Of the 107 CECTs performed, 11 false-positive and 3 false-negative readings were identified, resulting in a sensitivity of 92%, specificity of 85%, PPV of 75%, NPV of 95%, and an overall accuracy of 90%. Forty-three patients were imaged with ultrasound and CECT, and CECT had significantly better sensitivity and accuracy (30% versus 92% and 69% versus 88%, P<0.01). With regard to clinical management, 100% (36/36) of patients with appendicitis, and 4.2% (3/71) of patients without appendicitis underwent appendectomy. Therefore, the overall negative appendectomy rate was 7.6% (3/39). CONCLUSIONS: CECT is a useful diagnostic imaging modality for patients suspected of having acute appendicitis but with equivocal clinical findings and/or physical exams. CECT is more sensitive and accurate than ultrasound and is particularly useful in excluding the diagnosis of appendicitis in those without disease.